Improvement in adjustable blackboards



P. W. MUELLER.

Adjustable Blackhoards.

Patented Nov. 25,1873.

ATTMNEYS.

UNITED STATES PATENT OEEIoE.

PETER w. MOELLER, on NEW YORK, N. Y.

IMPROVEMENT IN ADJUSTABLE BLACKBOARDS.

Specification forming part of Letters Patent No. 144,917, dated November 25, 1873; application filed October 25, 1873.

To all whom it may concern:

Be it known that 1, PETER W. MoELLEE, of the city, county, and State of New York, have invented a new and useful Improvement in Adjustable Blackboards, of which the following is a specification:

Figure 1 is a front view of my improved blackboard, part being broken awafi to show the construction. Fig. 2 is a vertical section of the same, taken through the line m 00, Fig. 1. Similar letters of reference indicate corresponding parts. My invention has for its object to furnish an improved blackboard, for use in schools and other places, which shall be so constructed that it may be raised and lowered to adjust it to the height of the person using it, and according to the part of the board to be used, and which shall be so arranged that one part of the board, when filled, may be raised and the operation continued upon the other part. The invention consists in the combination of the two blackboards and the suspension-cord with theframe, grooved upon the inner surfaces of its side bars to receive the edges of the said blackboards; and in the grooves of one of the side bars of the frame, made deeper in their lower parts to enable the boards to be removed and turned,

as hereinafter fully described.

A represents a frame consisting of two side bars connected at them upper ends, and at or near their lower ends,by cross-bars. The lower ends of the side bars of the frame A may have feet B attached to them to support the frame and boards; or the frame may be secured to a wall, as the circumstances of the place where it is to be used may require. In the inner sides of the side bars of the frameA are formed t'wo longitudinal grooves to receive the side edges of the two boards 0, so that the said boards may be slid up and down. D is a cord, the ends of which are attached to the centers of the upper edges of the two boards 0, and

which passes over a pulley, E, pivoted to the center of the top bar of the frame A.

By this construction the two boards will balance each other, so that either may be low ered for use and adjusted at any desired height.

In the lower part of one of the side bars of the frame A the grooves are deepened for a little more than the height of the board 0, so that by pushing the lower board sidewise into the deepened part of its groove the other end may be swung out and the board removed from the frame. This construction enables a board to be conveniently turned when it is desired to use its other side.

By this construction the diagram or statement of a problem may be placed upon one of the boards and that board raised, and the solution placed upon the other board or a geometrical diagram, a map, or other drawing may be made upon one of the boards, which may then be raised, and the other board used.

By this construction much more available blackboard-surface may be obtained than with other arrangements.

Having thus described my invention, I claim as new and desire to secure by Letters Patent 1. The combination of the blaekboards G O, counterbalanced by each other, and suspension-cord L with the frame A, grooved upon. the inner surfaces of its side bars to receive the edges of said blackboards, arranged to operate substantially as herein shown and de scribed.

2. In combination with the blackboards O G, the grooves in the frame A, made deeper in their lower parts, at one side, to enable the boards 0 to be removed and turned, substan tially as herein shown and described.

PETER W. MOELLER.

Witnesses:

J Aivrns T. GRAHAM, T. B. llIOSHER. 

